Why Is My Vision Blurry?

Blurred vision is one of the most common eye complaints, and one of the most misunderstood. It can range from a minor nuisance caused by tired eyes to an early warning sign of a serious medical condition. Understanding what lies behind blurry vision is the first step to protecting your sight.

This guide covers the most clinically recognised causes, what to look out for, and when you should seek urgent attention.

Refractive errors are the single most frequent cause of blurred vision, affecting hundreds of millions of people worldwide. They occur when the shape of the eye prevents light from focusing correctly on the retina, resulting in a blurred image.

The main types are:

Myopia (short-sightedness), distant objects appear blurry, while close objects are clear

Hyperopia (long-sightedness), close objects are out of focus; distant objects may also blur in more severe cases

Astigmatism, an irregularly shaped cornea causes blur at all distancesPresbyopia, age-related stiffening of the lens, typically noticed from the mid-40s onwards, making close reading difficult

Refractive errors are almost always correctable with prescription glasses, contact lenses, or laser eye surgery. An up-to-date pair of prescription glasses is often all that is needed to restore sharp, comfortable vision.

A cataract is a clouding of the eye's natural lens, which sits behind the iris. It develops slowly, often over years, and is closely associated with ageing. Although other factors such as UV exposure, smoking, and certain medications can accelerate its onset.

Common symptoms include blurred or hazy vision, increased sensitivity to glare and bright lights, difficulty seeing in low light, and colours that appear faded. The gradual nature of the change means many people only realise how much their vision has deteriorated when tested.

Cataracts are the leading cause of vision impairment globally. In the UK, cataract surgery is one of the most frequently performed NHS procedures, and the outcomes are generally excellent. Most patients experience a significant improvement in clarity after the lens is replaced.

Dry eye syndrome occurs when the tear film, the thin layer of moisture covering the front of the eye, is either insufficient in quantity or poor in quality. This instability directly affects visual clarity, producing blur that tends to fluctuate throughout the day and often temporarily improves after blinking.

The condition is more common in older adults, contact lens wearers, and those who spend extended time in front of screens. Air-conditioned or centrally-heated environments can worsen symptoms.

Treatment ranges from lubricating eye drops and warm lid compresses to prescription anti-inflammatory medication in more persistent cases. Addressing screen habits and staying hydrated also makes a meaningful difference.

Glaucoma is a group of conditions characterised by damage to the optic nerve, most often associated with raised pressure within the eye. Glaucoma is the second leading cause of blindness worldwide. Chronic open-angle glaucoma causes no pain and progresses slowly, often going undetected until significant vision loss has occurred.

Blurred or reduced peripheral vision is a key symptom as the condition advances. Acute angle-closure glaucoma is a medical emergency. It can cause sudden, severe blurring, eye pain, headache, and nausea and requires immediate treatment.

Regular eye examinations are the most reliable way to detect glaucoma early. NHS guidelines recommend routine checks every two years for adults over 40, with more frequent testing for those at higher risk.

People with diabetes are at risk of diabetic retinopathy. A condition in which persistently high blood sugar levels damage the tiny blood vessels supplying the retina. As these vessels weaken, leak, or grow abnormally, vision becomes progressively distorted and blurred.

In its early stages, diabetic retinopathy may produce no noticeable symptoms at all. This is why annual diabetic eye screening is a critical part of diabetes management in the UK. Caught early, laser treatment and anti-VEGF injections can stabilise vision and prevent further deterioration.

Several additional factors can contribute to blurred vision:

Sudden blurred vision, particularly in one eye, should always be taken seriously. Seek immediate medical attention if blurred vision is accompanied by:

• Severe headache, facial drooping, or difficulty speaking (possible stroke)
• Eye pain, nausea, or seeing halos around lights (possible acute glaucoma)
• Flashes of light, new floaters, or a shadow across your vision (possible retinal detachment)

A routine eye examination can detect many causes of blurred vision. Refractive errors, early cataracts, glaucoma, and diabetic changes often before symptoms become noticeable. Adults are recommended to have an eye test at least every two years. Those with diabetes, a family history of glaucoma, or existing eye conditions may need more frequent checks.

NHS, blurred Vision

Healthline, blurry Vision: Causes, Diagnosis, and Treatment (medically reviewed, 2026)

Harvard Health Publishing, what Could Be Causing Your Blurry Vision?

Manchester Royal Eye Hospital (NHS), diabetic Eye Disease